Anions and electron-deficient aromatic rings.

摘要

More than two-thirds of all enzyme substrates and cofactors are anionic, emphasizing the essential role that anions play in biological processes. Moreover, anions can have detrimental effects on the environment by causing ground water contamination when anions such as perchlorate, phosphate and nitrate develop in intolerable levels. Owing to the prevalent nature of anions, traditional strategies employed to target anions---including hydrogen bonding, metal ion coordination and electrostatic interactions---have been extensively studied. An alternative approach to anion binding would complement the powerful array of existing techniques. Recently, in the supramolecular chemistry community, new insight has been cast on how anions attractively interact with electron-deficient arenes, suggesting that aromatic rings are a viable anion binding strategy to balance existing methods.;Chapter I provides a historical perspective of anions interacting with electron-deficient arenes. This outlook has its origins in the late 1800s with the discovery of colored charge-transfer complexes between donor and acceptor molecules and continues with the progression of the field leading up to the recent supramolecular fascination. Chapter II represents our initial efforts at measuring anion/arene interactions in solution. In particular, sulfonamide based hydrogen bonding receptors were developed with pendant aromatic rings to test the strength of anion/arene interactions in solution. Complementary computational chemistry and crystallography were utilized to supplement the solution studies. Chapter III describes our quantum calculations and crystallographic efforts at using only electron-deficient arenes to bind halides. A Cambridge Structure Database survey supports our emphasis of understanding multiple anion/arene interactions. Chapter IV illustrates how tripodal anion receptors can be developed to bind anions using only electron-deficient aromatic rings. Furthermore, subtle changes in anion binding geometries are observed with isomeric receptors and corroborated with Density Functional Theory calculations. Chapter V is dedicated to the preparation of electron-deficient anion receptors that are conformationally stabilized by hydrogen bonds. Chapter VI is committed to using our knowledge of anion binding to study a series of ethynyl-pyridine sulfonamides capable of hydrogen bonding to small molecules and anions. In conclusion, Chapter VII is a summary and future prospective for the field of anion/arene interactions.;This dissertation includes previously published and co-authored material.